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• What is ESR?
• Explain the principle of erythrocyte
• Discuss mechanism of ESR?
• What are the factors affecting ESR?
• What are methods of estimating ESR?
• What is the clinical significance of ESR?
• What are the source of error while doing the
• Erythrocyte- red cell
• Sedimentation- settling
• Rate- amount in a given
• Also k/a ‘sed’ rate
• Non specific test indicative of inflammation
• It is used as an initial screening tool and also
as a follow-up test to monitor therapy and
progression or remission of disease.
• Easy to perform, inexpensive
• Inexpensive making it a widely used screening
• Inexpensive making it
widely used screening test
• Measure- how much red cell
will settle in a given time
• Unit-measured in mm/hrs
Why is the ‘hr’
When the anti coagulated blood is allowed to
stand vertically, the red cells will settle towards
the bottom of the tube till they form a packed
column in a given interval of time. The process
of sediment6ation is called ESR.
• ESR is determined by the interaction between
factors that promote (fibrinogen) and resist
(negative charge of RBCs - that repel each
• Normal RBCs settle slowly as they do not
form rouleaux. Instead, they gently repel each
other due to the negative charge on their
• Rouleaux are stacks of many RBCs that
become heavier and sediment faster.
• Plasma proteins, especially
fibrinogen, adhere to the red cell
membranes and neutralize the
surface negative charges,
promoting cell adherence and
• The ESR is directly proportional to
the weight of the cell aggregate
and inversely proportional to the
• Stage of rouleaux formation/aggregation- 10
• Stage of sedimentation/settling- 40 min
• Stage of packing- 10min
Factors affecting ESR
• Plasma factors
• Red cell factors
• Rouleaux formation
• Tube factor
• Tilting of tube
• Fibrinogen, globulin and cholesterol increase
ESR by decreasing negative charge of RBC.
Negative charge prevent the RBC coming
• Plasma albumin retards sedimentation of
• Lecithin- retard ESR
Red cell factor
– Increased in red cell mass- decrease ESR
– Decreased red cell mass- increased in ESR
– Microcyte sediment slowly and macrocyte
sediment rapidly than normocyte
– The shape of the erythrocytes can also affect
– Sickle cell retard ESR because abnormal cell
hamper rouleaux formation
– Spherocytic cells also sediment at a slow rate
Red cell factor
• When RBC aggregates to
form a rouleaux and settle
down the area is much less
than sum of the area of
• Hence it is important
factor that increase ESR
• Women has slightly higher
ESR then men because of
their low PCV.
• The ESR begins to increase about third
the month and return to normal about
four week after delivery.
• Test should be done at 20-25⁰ C
• Higher temperature cause false high
results due to reduction in plasma
• Always bring refrigerated blood at RT
• Rise in every 3⁰ ESR increase by 1mm
• Test should be done within two
hours of collection
• EDTA sample should be kept at
4°C if delayed but should be
performed within 6 hours.
• K2EDTA or tri-sodium citrate should
• Heparin alter cell membrane potential
and should not be used
• ESR is greater with longer tube
• Inner diameter should be 2.5mm or
more to overcome capillary
Position of tube
• Tube should be perfectly vertical
• ESR increase as the RBC slide down
along the lower side
• Angle of 3⁰ from vertical can
increase ESR by 30℅
Hemolysed or clotted sample
• It retard ESR
• Clot trap fibrinogen hence,
no rouleaux formation occur
• Direct sunlight on ESR tube increase ESR
• Drugs such as dextran, methyldopa, oral
contraceptives, penicillamine procainamide,
theophylline, and vitamin A can increase ESR,
while aspirin, cortisone, and quinine may
• It is closed at one end
• length- 110 mm long
• Internal bore diameter 2.5mm.
• Tube is calibrated on both sides:
0-10 and 10-0.
• EDTA blood
• Wintrobe tube
• Wintrobe stand
• ESR needle
The procedure must be performed within 2 hours of
• Mix the anti coagulated blood thoroughly.
• Fill the wintrobe tube by using Pasteur pipette
upto mark 0.
• Place the tube vertically in a stand.
• Note the ESR at the end of 1 hour.
• Male=0-10 mm in 1st hour
• Female=0-20 mm in 1st hour
• Simple and widely used method
• Method recommended by ICHS
• Trisodium citrated
• 1.6 ml of blood is mixed
with 0.4 ml of TSC
• Westergren tube
• Westergren stand
• Rubber bulb
• Length= 30cm
• Internal bore diameter= 2.5mm
• Can hold about 1ml of blood
• Open at both end
• Calibrated from top to bottom: 0-200mm
• Mix the blood thoroughly.
• Draw blood into the tube up to mark ‘0’ with
the help of rubber bulb.
• Wipe out blood from bottom of the tube.
• Transfer the tube to westergren stand and
stand it vertically.
• Record the time and take reading.
• Male= 0-5mm in 1st hour
• Female=0-7mm in 1st hour
• More reliable and gives
• More blood is required
• Difficult to fill the blood in
• PCV cannot be done
• Mouth pipetting may be
Modified Westergren Method
• EDTA blood is used instead of citrate.
• 2ml of EDTA blood is diluted with 0.5 ml
of 3.8% TSC or 0.85% NaCl
• Undiluted blood gives poor precision.
VES-MATIC 20 instrument
• It is designed to measure 20 blood
• Result are comparable to Westergren
• results are available in approximately
Blood is collected in a special cuvette
Sample is mixed by instrument
Sample is allowed to stand
at 18⁰ slant from vertical
Data are elaborated and
ESR STAT PLUS
• It is centrifugation based method.
• Provides results in 5 minutes.
Sample is placed in centrifuge
Infrared laser tracks the erythrocyte plasma interface and takes multiple measurements
Linear portion of sedimentation is identified
Software algorithm to determine ESR result
• The filled Sediplast Westergren pipet is placed
into the SEDIMAT automated ESR reader,
which accelerates sedimentation under
• The reader displays the results of each sample
on an LCD display after 15 minutes.
• The results are also stored in memory and can
be printed out.
Zeta Sedimentation Ratio
• The ZSR is performed using a special, small-bore
capillary tube that is filled with blood and spun
for 3 to 4 minutes in a special centrifuge called
• Centrifuge alternately compacts and disperses
the RBCs under standardized centrifugal force
• Tube is then read on a special reader to obtain a
value called the zetacrit
• It is rapid, corrects for anemia, and requires only
a small blood sample, which is desirable for
Advantages of automated methods
• Save technician time
• Provide increased safety because the
need for sample manipulation is
• Interface with laboratory information
• Use smaller sample volumes
• Provide more rapid results
Source of error
• Improper ratio of blood and
• Hemolysed sample.
• Clotted blood.
• Presence of air bubbles.
• Error due to sunlight, vibration, small
bore size, dirty and wet tube.
• Delay in performing the test.